<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>按钮</title>
    <style>
        div{
            margin-left: 120px;
            height: 120px;
        }
        a{
            line-height: 58px;
            text-align: center;
            text-decoration: none;
        }
        .bg1,.bg2,.bg3,.bg4{
            height: 58px;
            width: 120px;
            display: inline-block;
            background-repeat: no-repeat;
        }
        .bg1{
            background-image: url(img/bg1.png);
        }

        .bg1:hover{
            background-image: url(img/bg11.png);
        }
        .bg2{
            background-image: url(img/bg2.png);
        }

        .bg2:hover{
            background-image: url(img/bg22.png);
        }
        .bg3{
            background-image: url(img/bg3.png);
        }

        .bg3:hover{
            background-image: url(img/bg11.png);
        }
        .bg4{
            background-image: url(img/bg1.png);
        }

        .bg4:hover{
            background-image: url(img/bg11.png);
        }

    </style>
</head>
<body>

<div>
    <a href="#"  class="bg1">wo</a>
    <a href="#"  class="bg2">who</a>
    <a href="#"  class="bg3">what</a>
    <a href="#"  class="bg4">why</a>
</div>
</body>
</html>